dt-bindings: iio: bmc150_magn: Document and fix missing compatibles
The driver supports also BMC156B and BMM150B. Add existing compatibles
marking the BMM150B one as deprecated (due to redundant suffix "_magn"
because the device unlike two others is a magnetometer only). Introduce
a new, proper compatible for the deprecated one.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>